Q. 4.59 - An Introduction to General, Organic, and Biological Chemistry

Question

Place the elements in each set in order of decreasing atomic size.
a. Al, Si, Mg
b. Cl, I, Br
c. Sb, Sr, I
d. P, Si, Na

Step-by-Step Solution

Answer

Part(a) The elements in order of decreasing atomic size are $\mathrm{Mg}>\mathrm{Al}>\mathrm{Si}$

Part(b) The elements in order of decreasing atomic size are $\mathrm{I}>\mathrm{Br}>\mathrm{Cl}$

Part(c) The elements in order of decreasing atomic size are $\mathrm{I}>\mathrm{Sb}>\mathrm{Sr}$

Part(d) The elements in order of decreasing atomic size are $\mathrm{Na}>\mathrm{Si}>\mathrm{P}$. 

Part(a) Step 1 : Given information

We are given Al, Si, Mg  atoms. We have to place the elements in order of decreasing atomic size.

Part(a) Step 2 : Simplify

The trend of atomic size on our periodic table so from left to right across a period, atomic size decreases as there is an increase in nuclear charge, pulling the electron shells closer and from bottom to top, the atomic size also decreases. So for aluminum, silicon, and magnesium. So Mg would be the largest, followed by Al, followed by Si.

$Mg>Al>Si$ 

Part(b) Step 1 : Given information

We are given Cl, I, Br  atoms. We have to place the elements in order of decreasing atomic size.

Part(b) Step 2 : Simplify

The trend of atomic size on our periodic table so from left to right across a period, atomic size decreases as there is an increase in nuclear charge, pulling the electron shells closer and from bottom to top,  atomic size also decreases. 

Therefore in Cl, I, Br , I would be largest followed by Br followed by Cl.

$\mathrm{I}>\mathrm{Br}>\mathrm{Cl}$

Part(c) Step 1 : Given information

We are given Sb, Sr, I  atoms. We have to place the elements in order of decreasing atomic size.

Part(c) Step 2 : Simplify

The trend of atomic size on our periodic table so from left to right across a period, atomic size decreases as there is an increase in nuclear charge, pulling the electron shells in closer and from bottom to top, the atomic size also decreases.

Therefore in Sb, Sr, I , I would be largest followed by Sb followed by Sr.

$\mathrm{I}>\mathrm{Sb}>\mathrm{Sr}$

Part(d) Step 1 : Given information

We are given P, Si, Na  atoms. We have to place the elements in order of decreasing atomic size.

Part(d) Step 2 : Simplify

The trend of atomic size on our periodic table so from left to right across a period, atomic size decreases as there is an increase in nuclear charge, pulling the electron shells in closer and from bottom to top, the atomic size also decreases. 

Therefore in Na, Si, P , Na would be the largest followed by Si followed by P.

$\mathrm{Na}>\mathrm{Si}>\mathrm{P}$